Sand core dipping machine



Feb. 14, 1956 JOHNSON ET AL 2,734,481

SAND CORE DIPPING MACHINE Filed Oct. 27, 1952 3 Sheets-Skeet 1 INVENTORSBER TIL. JoH/vso/v WILLARD C. SHAW M A TTO mvsys Feb. 14, 1956 JOHNSONETAL 2,734,481

SAND CORE DIPPING MACHINE Filed Oct. 27, 1952 3 Sheets-Sheet 3 INVENTORSBERT/L Jon-5o- WILLARD C. SHAW Zia/v ATTORNEYS United States Patent SANDcone DIPPING MACHINE Bertil Johnson and Willard C. Shaw, Anderson, lnd.,as-

signors to General Motors Corporation, Detroit, llilClL, a corporationof Delaware Application October 27, 1952, Serial No. 317,004

7 Claims. (Cl. 118-421) This invention relates to the dipping of coreelements or units used in a foundry, such as sand cores used in thecasting of various structures. The sand cores are of rather fragileconstruction to such an extent that they might be fractured or destroyedby the shock of moving or stopping their motion suddenly.

In the present instance trays of sand cores are loaded in an invertableor rotatable rack and are supported in such position that a bucket ofcoating material may be raised to such a position beneath the racks thatthe core units may be dipped in the core coating material withoutmovement of the core units themselves. The normally immersed bucket in asupply of core coating material has a flap valve for replenishing ofcoating material during movement of the bucket, and in its lowestposition actuates a switch that permits rotation of the rack in thatposition only. Power means are provided for raising the bucket, and forrotating the rack, including the use of electro fluid valves with fluidpressure actuators, and switches. Power means rotates the rack about ahorizontal axis through 180, and includes a cam plate on the shaft ofthe rack and a pivoted link connected with an actuator, that effects aslow start and a slow stop motion of the rack at both ends of theactuator movement. The cam and link relation is such that theintermediate movement between the start and stop of the rack rotation isaccelerated from the beginning to the mid point and is then decelerated.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred embodiment of the present invention isclearly shown.

In the drawings:

Fig. l is a vertical section through a clipping machine, showing therelation of supply tank bucket, rotatable rack and power means foroperation thereof.

Fig. 2 is a side view of the machine showing the rack invertingmechanism and linkage, substantially as indicated by the arrow of Fig.1.

Fig. 2A illustrates the intermediate step during rack rotation.

Fig. 3 tion.

Fig. 4 is a sectional view of the machine as indicated by the line andarrows 4-4 of Fig. 1.

Fig. 5 is a similar view with parts in a different position.

Fig. 6 is a circuit diagram of the control circuit.

The core dipping machine illustrated in the drawings comprises aplurality of post members, such as 10 and 12, connected together at thetop by bridge member 14, a stringer 16 and such other structuralelements as may be necessary. Surrounding the lower end of the members10 and 12 there is a tank 18 resting on a sill or the like 20 adapted toreceive a supply of coating material 22, in this case slurry for coatingsand cores.

is a similar view with the rack in another posi- Within the tank thereis a rectangular bucket 24 that is normally immersed in a supply ofcoating material 22 with its top edge 26 below the level of the coatingmaterial 22. At opposite ends of the bucket there are eye pieces 28through which extend rods 30 upwardly and through a plate 32. The rods30 and plate 32 constitute a bail for the bucket 24, and the plate 32 isfitted with screw 34 anchored against turning by cap screw 36, the screw34 having adjustable connection with a rod 38 connected with a piston ina fluid pressure cylinder 40. In the bottom wall 42 of the bucket thereis an opening 44 covered by a flap valve 46 secured thereto at 48.

By this construction, the bucket 24 is adapted for vertical movementupwardly and downwardly in response to action of the fluid pressuredevice 48. The up and down movement of the bucket is guided by the framemembers 10, 12 and the like. In Fig. 4 the bucket is shown in itslowermost position where it is completely immersed in the coatingmaterial 22. In Fig. 5 the bucket is shown in elevated position and inwhich it is completely filled with the coating material 22. From thiselevated position, downward movement of bucket 24 permits coatingmaterial 22 from the tank 18 to flow through the opening 44 covered bythe flap valve 46 so that the bucket 24 will always be filled with thecoating material. When the coating material 22 has a tendency toseparate, or the solid material therein tends to settle, raising andlowering of the bucket into and out of the supply will keep the materialagitated and thoroughly mixed. In the elevated position as shown in Fig.5, the bucket is raised to such a position as to partially immerse acore supporting rack 50 and any core elements or units 52 supported onthe underside of the rack.

In this case, the rack 59 is mounted on a horizontal shaft 54 which issupported at one end by a pillow block 56 carried by the stringer 16,and journaled at the other end 53 in post member 10. The rack 50includes a pair of plates 60 secured on opposite sides of the shaft 54and to the opposite edges of plates 69 are secured end plates 62, theedges of which are secured to rails 64 spaced from cleats 66. Thespecified arrangement of the end plates 62, the rails 64 and the cleats66 provide opposing ways 68 for the reception of trays 70 supporting aplurality of the core elements or units 52. 7 As shown in Figs. 4 and 5this rack 5%) provides for the reception of two trays 70 both in ahorizontal position and either above or below the shaft 54, forrotation, and thereby inverting the position of the core elements.According to the showing in Fig. l, the rack 50 is in position to exposethe ways 68a as accessible between the post members 12 for loading froma table, shelf or platform 72 associated with the front of the machine.Rotation of shaft 54 through a half circle or 180, will invert the rackso that the tray of cores in the ways 63a is on the underside of therack, while the ways 68b are uppermost for loading with a tray of cores.In Fig. 4 the rack 50 is shown with a load of core members in both theupper ways and the lower Ways, and Fig. 5 shows the core members in thelower ways being dipped into the coating material carried by the bucket24.

The rack 50 is rotated about the horizontal shaft 54 for inversion ofthe core members or units by means of a fluid pressure actuator 74anchored by the brackets 76 secured to the post and frame member 10. Theactuator '74 provides a piston rod 78 pivotally connected at 80 to alink 82 pivotally mounted at 84 to a block 86 attached to the framemember 10. The link 82 is provided 'with two cam rollers 88 and 90, eachof which engages with a cam slot 92 or 94 in a cam plate 96 secured onthe rack shaft 54 by a key 98. Linear motion of the actuator rod 78oscillates the link 82 about the pivot point 84 dur ing which time thecam rollers 88 and 90 traverse the cam slots 92 and 94 from the positionof Fig. 2 through the relation shown in Fig. 2A to the position shown inFig. 3.

During that traverse the link 82 is rotated through a comparativelysmall angle, but the rack 50 is rotated 180. During this rotation, link82 can move at a uniform rate of speed but the cam relation with respectto plate 96 is such that the beginning and ending of rack movement isrelatively slow, followed by an accelerated movement toward the positionin Fig. 2A, and thence a decelerated movement toward the position shownin Fig. 3.

That is brought about by the relation of the cam rollers and cam slots.Here, the cam slots 92 and 94 are generally similarly shaped but beingin an allochiral relation. As seen in Fig. 2, the end portion of the camslot 94 is substantially parallel or tangent to the arc of motion ormovement of the cam roller 90 when the link 82 rotates about the pivot84. Similarly, the engaging portion of the cam slot 92 bears a similarrelation with respect to the cam roller 38. In that instance, movementof the link 82 through a comparatively large angle will effect butslight angular movement of the cam plate 96. By the time the rack 50 hasbeen rotated half-way through its possible movement, the relation of thecam plate and link reaches the position shown in Fig. 2A, wherecontinued rotation of link 82 has the greatest effect on 96 as torelative angular movement. Now, the rollers 88 and 90 have reached apoint in the cam slots where their angular movement is substantially atright angles to the engaging faces of the respective cam slots.Continued rotation of the link 82 brings about the relation shown inFig. 3. The last end of the movement of the rack is decelerated becauseof the rollers traversing an are substantially parallel with the engagedsurfaces of the respective cams. Thus, in the rotative movement of therack 50, there is a slow pickup of angular movement which is acceleratedthrough the intermediate path of rotation and then ends in a cushionedstopping movement. Thus relatively fragile core members loaded in therack may be inverted to the dipping position and returned to the loadposition without shock or jar which might cause them to fracture ordisintegrate.

The raising and lowering of the bucket and the rotation of the rack areaccomplished in a definite sequence through the agency of anelectrofluid control system somewhat as shown in Pig. 6 for effectingoperation of the fluid pres sure actuators 4t and 74. The rack cannot berotated while the bucket is in any position other than at the bottom ofthe tank substantially shown in Figs. 1 and 4. When the bucket is in thelowest position a pin 1% operates a microswitch M81 to keep it in aclosed contact position. When the bucket is in a raised position a pinHi2 actuates a microswitch MSZ to open circuit a relay R1. When the rackis in one position, as shown in Fig. 2,

a microswitch M84 is in one circuit closed position to condition asolenoid valve S1 for operation, and when the rack is in the reverseposition shown in Fig, 3, switch M84 permits electroconnections with asolenoid valve S2.

The switch M34 is in the nature of a selector switch, and

its operation is effected by engagement or disengagement of the camplate 96. The pivoted link 82 has a symmetrical cam portion 194 foroperating a microswitch M53 for controlling the solenoid valve S3, inturn controlling the flow of fluid pressure to and from the actuator 74.

With specific reference to Fig. 6, electric current is supplied througha main switch SW1 to conductors 1G6 and 1&8, which feed three parallelcircuits 110, 112 and 114. Circuit 110 includes a push button switch PB1normally open, the microswitch MS1 normally open, but closed when thebucket is in the lower position, and the microswitch M84 which connectseither solenoid valve S1 or S2. Circuit 112 includes a pair of contactsC1 normally open, microswitch MS2 which is normally closed but open whenthe bucket is in the raised position, and the winding of relay R1 whichcontrols the contacts C1, C2 normally open. The circuit 114 includesmicroswitch MS3 normally connected with circuit 112, but actuated by thepivoted link 82 to complete circuit 114 through normally open contact C2and a solenoid actuated valve S3. The

solenoid valve S3 controls the flow of fluid pressure to actuator 49 forraising and lowering the bucket. The solenoid valves S1 and S2 controlthe flow of fluid pressure to and from the actuator 74 for controllingthe rotation or inversion of the rack. The relay when energized effectsthe closing of contacts C1 and C2.

When the machine is in condition for operation, the circuit will beclosed through solenoid valves S1 or S2 except for push button switchPBl. Circuit 112 will be closed through part of circuit 114 includingmicroswitch M53 in its upper position connecting with microswitch M82,the relay R1 operating to close contact C1. The solenoid valve S3 incircuit 114 will be deenergized even though contacts C2 are closed,because switch M83 is in the upper position. For rotating the rack theoperator closes push button switch PBl by which either solenoid valve S1or S2 is energized to effect operation of the actuator 74 which rotatesthe rack. When the rack rotates or turns over the microswitches M54 andMS3 are reversed, which cuts in the other solenoid valve S2 or Si, andcompletes the circuit 114 for energization of the solenoid valve S3.Solenoid valve S3 controls the flow of fluid pressure to and fromactuator 40 for raising the bucket to the upper position. As the bucketraises, microswitch M51 is opened to deenergize the solenoid valves S1or S2 and microswitch M52 is then opened which deenergizes relay R1followed by opening contact C1 and C2. Solenoid valve S3 being openedcircuited the bucket is lowered, which recloses microswitch M82 andfinally closes microswitch MSl.

That completes the sequence of operations and conditions the machine fora second operation. The rack with a load of core units has been rotatedto place them on the underside of the rack, and the bucket has beenraised with its supply of coating material to the position shown in Fig.5 where the core elements are coated followed by lowering the bucket tonormal position. A second closing of the push button switch P131 firsteffects closing of the circuit 110 which energizes the other of thesolenoid valves S1 or S2 effecting rotation or inversion of the rack.Now, the coated core units will be on top of the rack, and may bereplaced by a new set to be coated. The microswitch M51 is provided sothat the rack cannot be rotated except when the bucket is in the bottomposition.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. A core dipping machine comprising, in combination, a tank of dippingmaterial, an invertible core supporting rack rotatably supported oversaid tank, a buck et immersed in the tank beneath the said rack adaptedto be lifted for raising a quantity of dipping material, power means forinverting the rack when the bucket is in the bottom of the tank, saidmeans for inverting the rack including a cam plate and a crank armhaving interengaging means for accelerating the rotating motion of therack from a slow start of the said inversion and for decelerating thestop of said inversion, and means preventing anyinversion of the rackwhile the bucket is being lifted.

2. A core dipping machine comprising in combination, tank meansproviding a supply of core dipping material, a core supporting rackrotatably mounted over said supply, means for rotating said rack from aloading position to a dipping position, a vertically movable bucket forlifting a quantity of dipping material from said supply tank for coatingcores supported by said rack, means for rotating said rack and meanspreventing rotation of the rack when the bucket is in other than itslowermost position.

3. A core dipping machine comprising in combination, means providing asupply of core dipping material, a bucket normally immersed in the coredipping material, means for raising the bucket and a quantity of dippingmaterial above the level of the core dipping material, a rotatable rackfor supporting a tray of core members over the bucket means for rotatingthe rack for moving the trays from a loading position to a dippingposition, means controlled by the bucket preventing the rotation of therack while the bucket is being raised, and means permitting rotation ofthe rack when the bucket returns to its immersed position.

4. The combination set forth in claim 3 wherein the bucket has a flapvalve for admission of dipping material to the bucket while it is beingimmersed.

5. In a core dipping machine the combination comprising, a rotatablerack for supporting trays of core units to be dipped, means for rotatingthe rack from a core loading position to a core dipping position, saidrack rotating means including; a cam plate rotatable with said rack, apivoted link adapted to rotate said cam plate, and means connecting saidcam plate and pivoted link, said means being adapted for starting andstopping the rack rotation slowly and without shock.

6. The combination set forth in claim 5 wherein the connecting meansinclude a cam plate having S-shaped slots therein and the link includesrollers engageable in said slots.

7. The combination set forth in claim 6 wherein, the connecting meansincludes a cam plate having a pair of curved cam slots, and the pivotedlink provides a pair of rollers engageable in the cam slots, said camslots being of allochiral relation and having portions cooperable withthe cam rollers to efiiect relatively small angular movement of the rackat the start of rotation of the pivoted link and at the stop of movementthereof, as the rollers traverse said slots.

References Cited in the file of this patent UNITED STATES PATENTS1,064,235 McCan June 10, 1913 1,258,071 Winter Mar. 5, 1918 1,585,880Schnell May 25, 1926 2,159,850 Haynes May 23, 1939 2,529,488 CoppockNov. 14, 1950 2,617,163 Jeter et al. Nov. 11, 1952

